Ductile asphalt composition



United States Patent DUCTILE ASPHALT COMPOSITION George W. Ayers, Chicago, and Allen F. Millikan, Evanston, Ill., assignors to The Pure Oil Company, Chicago, 111., a corporation of Ohio N Drawing. Application December 28, 1951,

"Serial No. 263,991

5 Claims. (Cl. 196-452) It has been found that the addition of soft wax, a

by-product of the manufacture of microcrystalline wax, to an asphalt of zero ductility at about 77 F. results in a product which has excellent ductility, is not sticky, and is particularly suitable as an impregnant for coating of paper. Further, it has been found that the incorporation of certain solvent extracts from the solvent refining of lubricating oil fractions into compositions containing soft wax and asphalt further improves and enhances the physical properties of the finished asphalt blend and increases its stability under conditions of use.

It is known in the prior art that various wax hydrocarbons may be used to incorporate in asphalts for the purpose of increasing the water resistance or ability to resist wetting of asphalts and asphalt blends. Camp, in United States Patent 2,464,759, discloses the combination of wax crystals in asphalt in such a manner that the crystals outcrop at the surface of the asphalt and yield a non-wetting coating. Parafiin waxes for this purposes are preferably those which melt at around temperatures of'122 to 124 F. and not above 165 F. In coating strands of cloth with first an asphalt layer and secondly a coating of wax, it is taught in United States Patent 2,018,404 by Lamplough that the temperature of intercoating of the two materials is important so that the weld between the layers is improved, yet not so high temperatures that the sticky Wax penetrates too far into the coating. And, lastly, it is known that combinations of ordinary asphalt and wax or wax tailings or petroleum wax or still wax form a substitute for brewers pitch to line the inside of beer kegs. Here, the resultant composition is resilient, glossy, does not crack or dissolve in ordinary solvents, and may be easily cleaned.

It, thus, appears a common expedient to render asphalts wax-like or unctuous and lessening their tendency toward stickiness to incorporate small percentages of ozokerite, montan wax, hydrocarbon wax, and pyrogenous waxes. These waxes do not amalgamate permanently with the asphalt but tend to work their way into the surface in time and form a thin waxy film which will modify the characteristics of the mixture.

In addition, it is known that the proper balance of oil content of a paraflin wax is necessary as far as the ductile characteristics of the wax or compositions containing same are concerned. Parafiin and high melting point petroleum ceresine types of wax should have a low oil content as the presence of oil affects their tensile strength and texture. For the purpose of laminating,

coating, or impregnating papers and cloth, a soft waxcontaining composition is desirable. However, it is not possible in all instances to attain compatibility of asphalts and petroleum waxes, whether of the low oil content, high melting variety or the high oil, low, melting variety. Lower melting point waxes of the so-called microcrystalline variety are softer and of higher penetration. ,As such they are characterized by their plasticity, tackipresent.

Patented Sept. 4, 1956 ness, and good flexibility. They are more soluble in asphalt, oil, etc. Consequently, these lower melting microcrystalline waxes are used largely as modifiers for paraflin waxes, as for waterproofing and finishing compounds in the manufacture of textiles and paper coatings. Large amounts of the soft waxes will improve the flexibility and sealing strength, but will increase the plugging tendency. Consequently, it is felt that the present discovery of a by-product soft wax of relatively high oil content and of the low melting variety will increase the ductility of an asphalt in the presence of a stabilizing amount of phenol extract, a highly aromatic constituent, is contrary to the teaching of the prior art. Although soft waxes are used to increase the ductility of asphalts, the particular soft waxes are highly refined and are inherently flexible, ductile and have high sealing strengths. The soft waxes of the present invention are without flexibility, very low melting point, have a relatively high oil content, a low sealing strength, and are ordinarily considered as a waste product.

Accordingly, it is the fundamental object of this invention to provide an asphalt composition having desirable characteristics of penetration, ductility, and softening point for use as an impregnant or coating agent.

A second object of this invention is to provide a wax composition comprising asphalt incorporated with a small amount of soft wax by-product from the manufacture of microcrystalline wax, having excellent ductility.

A third object of this invention is to provide an asphalt wax composition containing small amounts of solvent extracts from the refining of lubricating oil stocks wherein a composition of improved stability is attained.

Other objects and advantages of this invention will become apparent as the description thereofproceeds.

The three ingredients of the present compositions are from particular sources. Although any asphaltic material, either natural or pyrogenous, maybe used in the present compositions, it is preferred that the so-called propane deasphalter bottoms produced from the deasphalting of lubricating oils as in the manufacture of bright stock from vacuum still bottoms be used. This asphalt being insoluble in propane and precipitated by propane is first freed of traces of propane and is known as propane deasphalter bottoms. This material has all the appearances of a good grade of asphalt, but it is very brittle and has no ductility. Typical tests on a sample of propane deasphalter bottoms are: penetration at 77 F., 3; ductility at 77 F., 0; softening point, 173 F.; C. O. C. flash, 635 F.; C. O. C. fire, 705 F.; P. M. flash, 505 F.; ash, 0.08%; solubility in carbon disulfide, 99.95%.

The asphalts contemplated in the present invention are not ductile asphaltic bitumens since the latter have not been subjected to propane treatment and are generally the result of vacuum distillations. The propane treatment takes out much of the petroleum resins and leaves asphalt containing largely hydrocarbons which qualify as asphaltenes. T hese asphaltene hydrocarbons are of lower molecular weight than the natural asphaltenes occurring in'such materials as Gilsonite.

The second ingredient of this invention comprises the soft wax which is a by-product from the manufacture of microcrystalline wax. During this process, the waxy hydrocarbons are dissolved in methyl ethyl ketone and chilled, whereupon the microcrystalline wax is separated in crystalline form. The methyl ethyl ketone carries away the various proportions of mineral oil and soft wax Separation of the methyl ethyl ketone from the remaining materialproduces the soft wax by-product, which is generally a waste product, and the soft waxes used herein will contain from 25 to 50 per cent of hydrocarbon oil. Upon separation of the wax content from the oil, the melting point of the pure wax will be about 145 F. or lower. The soft wax by-product is ordinarily fluent at room temperature and has a pour point of about 60 F. with some samples exhibiting pour points of 89 to 100 F. Tests'on a typical sample soft wax contemplated in thi'sinvention are as follows: A. P. I. gravity, 28.7";

C. O. C. flash, 565 C. O. C. fire, 635 'F.; S. U. S. viscosity at 100 F., 1257; .S. U, S. viscosity at 13071 546; S. U. S. viscosity at 210 F., 118.2; viscosity index, 115; maximum pour, +80 F.; N. P. A. color, 7+.

In order to demonstrate the present invention, tests were made on blendsof propane deasphalter bottoms and soft wax as well as on blends of propane deasphalter From Table I it is seen that the addition of soft wax or the combination of soft wax and phenol extract has increased the ductility of the blend to a maximum. These ductility measurements are made by'stretching a sample into a string or thread and measuring the length of elongation. The penetration of a useful composition containing soft wax and propane deasphalter bottoms may range from 15 to 17 at 77 F. and the softening point from 140 to 146 F. Likewise, compositions containing propane deasphalter bottoms with soft wax and phenol extract may have penetrations ranging from 10 to 14 at 77 F. and softening points of from 140 to 150 F. Compositions within the ranges just described will all have superior ductilities, which is the characteristic which establishes a criterion for paper coating and impregnating asphalticmaterials.

The ductile asphaltic compositionsprepared in accordance with this invention may contain up to 20 per cent of soft wax where no solvent extract is used. In those compositions containing both soft wax andsolvent extract, it is desirable that the total weight of these two materials does not exceed 20 weight percent. Maintenance of the proportions of the ingredients will insure superior ductilities without sacrifice of other physical properties. By varying the proportions of the ingredients, 1 it is possible to obtain compositions havingdifferent penetrations, ductilities, and softening points. In addition, compositions having particular adhesiveness, surface tension, solidify-ing point, or flow point may be obtained by variation of the proportions of the ingredients.

When extracts from the manufacture of neutral oils are used, the total amount of extract plus soft wax should not exceed about 10%. A minimum of 510% total soft Wax and lubricating oil extract is necessary in the asphalt blend to show appreciable ductility and a minimum of 4 5% of soft wax is necessary for appreciable effect on the tackiness of the blend. I

The solvent extraots used in accordance with this invention are obtained during the manufacture of neutral and bright lubricating oil stocks.

In a typicaloperation, desalted crude oil is first charged to a distillation unit where straight run gasoline, two grades of naphtha, kerosene, and virgin distillate are taken off, leaving a reduced crude residue. The reduced crude is continuously charged to a vacuum distillation unit where three lubricating oil distillates' are taken 011? as 5 side streams, alight distillate is taken 011 as overhead, and a residuum is withdrawn from the bottom of the tower. This residuum is'charged to a propane deasphalting unit wherein propane dissolves the desirable lubricating oil constituents and leaves the asphaltic materials. A typical vacuum residuum charge to the propane deasphalting unit may have an API gravity of 129, viscosity SUS at 210 F. of 1249, flash 585 F., fire.650 F., Conradson carbon residue of 13.9 weight .per cent and is black in. color. The deasphalted oil may have an API gravity of 21.5 to 21.8, viscosity SUS at 210 F. of 165-175, NPA color 6-7, flash 575 F, fire 640 F., and Conradson carbon residue of 1.72.0. The deasphalted oil and various lubricating oil distiilates from the reduced crude are separately subjected to solvent extraction for the separation ofnon=aromatic from aromatic constituents. Therefined oil or rafiinate from such processes after dewaxing is used as blending stocks and the solvent extract, containing the undesirable aromatic constituents, is the material found useful in accordance with this invention. Dewaxing of the raffinate produces a crude wax or petrolatum and bright'stock. The crude wax is again dewaxed with methyl ethyl. ketone to produce a microcrystalline wax and the soft wax by-product used in accordance with this invention.

For example, a Van Zandt crude oil with an API gravity of 33.1 was topped to remove such light fractions as gasoline, naphtha, kerosene, and a light lubricating distillate. The vacuum residue was a reduced crude having a viscosity of 1251 SUS at 210 F., 2.2 per cent sulfur, and an API gravity of 12.6. Afterapropane deasphalting, the oil had'a viscosityof 174 SUS at210 F. and an API gravity of 21.7. This deasphalted oil was treated with phenol to produce arafiinate from which a first dewaxing step produces petrolaturn and a second dewaxing step produces theby-productsoft wax. The extract phase from-the phenol treatment and the soft wax are ready for use in preparing compositions in accordance with this invention.

Other solvents than phenol may be used to obtain the extraction product used in accordance with this invention; for example, furfural or the Duo-Sol solution comprising liquid propane, phenol, and cresol may be used. When using phenol, it is possible to vary the characteristics of the extraction product considerably by adjustment of the amount of water present. A low V. I. cut maybe obtained by using a water solution of phenol during the. extraction and a high V. I. cut may be obtained by using anhydrous phenol. Following are the physical characteristics of typical extraction products from bright stock from Van Zandt crude oil which may be used in accordance with this invention.

TABLE H Certain characteristics of samples of extracts from lube oil'base stocks Extract API Pour Percent Percent Percent No. Gravity V1s./100 F. Via/130 F. Via/210 F. V. I. (Max. Wt. Wt.H v- Wt. Total F. Carbon drogen Sulfur The ductile asphalt compositions of the present invention are particularly adapted for use as impregnants, as coatings for paper, both in the manufacture of waterproof papers for wrapping and packing and waterproofing papers for insulating against heat, cold, or moisture. Paper products impregnated with the present compositions will have desirable weight per unit area, require only very thin coatings to attain the desired waterproofing characteristics, and exhibit the much desired ductility for folding and wrapping purposes without cracking and allowing the moisture to enter the contents. in addition, Wrapping papers formed using asphaltic compositions of this invention have the desirable bursting and tearing strengths and pliability necessary for wrapping papers. They are resistant to dampness, water absorption, and exhibit remarkable resistance to heat.

In addition, for use in coating papers the present asphaltic compositions may be used for coating fibers including linen, cotton, wool, bleached manila hemp, wood fibers, straw, esparto, and sawdust.

Although the present invention is not to be limited to any theories explaining the enhanced properties of the compositions described herein, one explanation may be the stabilizing effect of the petroleum resins present in the solvent extracts. These resins tend to mitigate the bleeding of the oil and the separation of the wax from the gel structure of the blends. Certain relationships exist between the properties of the soft wax and/ or solvent extracts and the physical properties of the finished asphalt blend. The soft wax should not contain more than 50 per cent oil if bleeding of the asphalt blend is to be avoided. The oil in the soft wax is of a type which is more compatible with asphalt than is ordinary lubricating oil. The soft wax also should not contain high melting point microcrystalline wax or parafiin wax from neutral oil manufacture, since the latter materials show low miscibility with the asphalt at ordinary temperatures. The quantity of soft wax in the asphalt blend should not exceed about 20 per cent since higher proportions result in a soft or oily product or tend to cause bleeding of the oil from the asphalt blend.

Any lubricating oil extract may be used in the asphalt blends of this invention, but the optimum amount of extract to be used will vary snmewhat with the type of extract. Extracts from bright stock manufacture are the most suitable. Extracts from the manufacture of intermediate V. I. bn'ght stock manufacture are preferred over those from high V. I. bright stock manufacture since the latter contains the greater proportion of high V. I. oil. Extracts having very low viscosity index are preferred. The viscosity index of the extract should be below and preferably below zero.

With the use of soft wax, in accordance with the present invention, the wax does not separate from the asphaltwax blend, but the mixture remains homogeneous and imparts the property of non-stickiness without the disadvantage of the out-cropping of wax crystals.

What is claimed is:

1. A ductile asphaltic composition for use in coating paper comprising at least about weight percent of propane insoluble asphaltic material, a minor portion of soft wax, and a minor portion of solvent extract containing petroleum resins from the refining of lubricating oils the total of said minor portions of soft wax and solvent extract not exceeding about 20 percent by weight.

2. A ductile asphaltic composition for use in coating paper comprising at least about 80 percent by weight of propane deasphalter bottoms, a minor amount of soft wax from the manufacture of microcrystalline wax, and a minor portion of phenol extract containing petroleum resins and obtained from the manufacture of lubricating oil bright stock the total of said minor portions of soft wax and solvent extract not exceeding about 20 percent by weight.

3. A ductile asphaltic material for use in coating paper comprising about weight per cent of propane deasphalter bottoms, about 5 weight per cent of soft wax from the manufacture of microcrystalline wax, and about 5 per cent by weight of phenol extract containing petroleum resins and obtained from the manufacture of lubricating oil bright stock.

4. An asphaltic composition for use in coating paper comprising about 90 weight per cent of propane deasphalter bottoms and 10 weight per cent of soft wax, said composition having the following characteristics: penetration at 77 F., 15-17; ductility at 77 F., 150+; ring and ball softening point, -146 F.

5. A ductile asphaltic composition for use in coating paper comprising about 90 weight per cent of propane deasphalter bottoms, about 5 weight per cent of soft wax, and about 5 weight per cent of extract containing petroleum resins and obtained from the manufacture of lubricating oil bright stock, said composition having the following physical characteristics: penetration at 77 F., 10-14; ductility at 77 F., ring and ball softening point, 140-150 F.

References Cited in the file of this patent UNITED STATES PATENTS 248,072 Warren Oct. 11, 1881 2,073,088 Anderson et al Mar. 9, 1937 2,215,551 Herrmann Sept. 24, 1940 2,492,848 Crouch et al Dec. 27, 1949 2,649,384 Anderson Aug. 18, 1953 

1. A DUCTILE ASPHALTIC COMPOSITION FOR USE IN COATING PAPER COMPRISIING AT LEAST ABOUT 8/ WEIGHT PERCENT OF PROPANE INSOLUBLE ASPHALTIC MATERIAL, A MINOR PORTION OF SOFT WAX, AND A MINOR PORTION OF SOLVENT EXTRACT CONTAINING PETROLEUM RESINS FROM THE REFINING OF LUBRICATING OILS THE TOTAL OF SAID MINOR PORTIONS OF SOFT WAX AND SOLVENT EXTRACT NOT EXCEEDING ABOUT 20 PERCENT BY WEIGHT. 